Tax / regulation procedure for a motor vehicle

Abstract

Tax / regulation procedures for a motor vehicle include the following steps: - Driver-side setting of a target speed for the vehicle and / or a target distance to a vehicle in front, - automatic detection of a need for downhill speed control, and - Automatic control / regulation of the motor vehicle to the target speed or a maximum speed and / or the target distance by means of individual wheel braking intervention when there is a need for downhill speed control, characterized by - automatic control / regulation of the motor vehicle to the target speed and / or target distance solely by adjusting the engine torque and / or a simple brake intervention and / or a transmission influence and / or a transmission shift influence, when there is no need for hill descent control, - whereby the need for downhill speed control is recorded when the specified target speed of the motor vehicle is less than a second speed threshold.

Description

[0001] The invention relates to a control / regulation method for a motor vehicle and a motor vehicle with automatic activation of a hill descent control.

[0002] State-of-the-art hill descent control (HOC) systems are known, particularly in all-wheel-drive vehicles. These functions maintain a relatively low vehicle speed during steep downhill descents. To do this, the driver must press a specific button in the vehicle and set the desired target speed. Cruise control functions and adaptive cruise control (ACC with or without stop-and-go function) are also known. These functions primarily control the speed or desired distance by changing the engine torque and / or by simple braking interventions.

[0003] It is an object of the invention to provide a method and a motor vehicle using the method, which are intended to increase both user-friendliness and to ensure driving stability, in particular when driving downhill.

[0004] DE 10 2007 009 860 A1 describes a method for controlling the speed of a motor vehicle when driving uphill. A differential signal is determined from an actual speed signal and a target speed signal. A control signal is determined based on the differential signal and an inclination signal. The control signal can be converted into a wheel-specific braking signal.

[0005] DE 199 25 368 A1 discloses a method for controlling a vehicle. A control variable, which influences the vehicle's speed, is only determined or applied when a downhill descent of the vehicle is detected. Downhill descent can be detected based on a signal from an inclination sensor and / or based on the vehicle's acceleration.

[0006] DE 10 2004 047 462 A1 discloses a device for longitudinal guidance of a vehicle, which has an operating device by means of which the driver can activate a follow-along function or a cruise control function. During the follow-along function, the vehicle speed is controlled between a standstill and a predetermined maximum speed such that the vehicle follows the preceding vehicle at a predetermined distance. Furthermore, the vehicle speed can be controlled to a target speed during the cruise control function.

[0007] WO 01 / 14 185 A1 describes a method for compensating for slope drag during HDC control. The brake pressure determined by the HDC control is increased by a compensation brake pressure depending on the road gradient, and the service brake is influenced by the sum of the brake pressures.

[0008] This problem is solved by the features of the independent claims. The subclaims relate to advantageous developments of the invention.

[0009] Thus, the invention is achieved by a control / regulation method for a motor vehicle, comprising the following steps: - setting by the driver a target speed of the motor vehicle and / or a target distance to a vehicle in front, - automatic detection of the need for downhill control, - automatic control / regulation of the motor vehicle to the target speed and / or the target distance merely by adjusting the engine torque and / or a simple braking intervention and / or a gearbox control and / or a gearbox control if there is no need for downhill control, and - automatic control / regulation of the motor vehicle to the target speed or a maximum speed and / or the target distance by means of a wheel-individual braking intervention when there is a need for downhill control.

[0010] "Driver-side setting" defines an action by the driver of the motor vehicle. The driver can specify the target speed and / or the target distance, preferably using buttons on the steering wheel or a steering column stalk. Automatic detection or automatic control / regulation describes a process that the motor vehicle performs independently without driver intervention. The proposed control / regulation method thus combines the previously separate functions of a hill descent control with a cruise control and / or a distance-controlled speed control function. This increases functional transparency for the driver, which on the one hand increases user-friendliness and on the other hand allows the driver to concentrate on essential safety-relevant matters. A switch previously required to activate the hill descent control is no longer necessary when using the method according to the invention.Furthermore, the control / regulation method according to the invention can be implemented in motor vehicles in a very simple manner, in particular by modifying software. The simple braking intervention, as used when there is no need for downhill control, merely distributes the braking torque between the front and rear axles, but does not provide any further control / regulation of the braking torques. In contrast, with active downhill control, i.e. when downhill control is necessary, deceleration is carried out with wheel-specific braking intervention. This wheel-specific braking intervention is used in particular when there is a need for downhill control and vehicle instability at the same time. When the vehicle automatically activates downhill control, various speeds are available to which the vehicle can be controlled.For example, if the target speed specified by the driver is within non-safety-critical limits, in particular less than a speed between 7 and 25 km / h, the vehicle will advantageously steer / regulate to this target speed. However, if this specified target speed is too high and, in particular, disproportionate to the actual gradient traveled, the vehicle will specify a maximum speed, and the vehicle will automatically steer / regulate to this maximum speed to ensure vehicle safety when driving downhill. A driving situation can be recognized as critical, especially downhill, even at speeds below 25 km / h. This is especially the case on steep gradients.

[0011] In a preferred embodiment, the need for downhill control is detected when the actual speed of the motor vehicle is below a first speed threshold, in particular below a speed between 7 and 25 km / h. At such a relatively low speed, it is possible that the vehicle is traveling downhill on relatively difficult terrain, and thus, it is proposed to activate downhill control in this range.

[0012] In addition, the need for hill descent control is detected if the specified target speed of the motor vehicle is below a second speed threshold, in particular below a speed between 7 and 25 km / h. In addition to or as an alternative to activating hill descent control based on the actual speed, hill descent control can be based on the target speed specified by the driver. The driver advantageously sets this target speed using a steering column stalk and / or a keypad on the steering wheel. The driver therefore only uses the control device for the cruise control and / or for the adaptive cruise control function. If the driver sets the speed to a value below the second speed threshold, hill descent control is automatically activated, which then ensures vehicle stability through individual braking interventions.

[0013] It is further preferred that the need for downhill control is detected when a road gradient is greater than a certain gradient threshold, in particular greater than 15%. This road gradient can be detected in a simple manner using longitudinal inclination sensors or indirectly via acceleration sensors in the vehicle. It is of course advantageous to combine this activation of the downhill control based on the road gradient with activation based on the target speed and / or actual speed. In this way, a distinction can preferably be made between a non-critical downhill drive, e.g. on a motorway, and a critical downhill drive, e.g. off-road or on difficult terrain, by only activating the downhill control when the sensors detect a certain gradient and, at the same time, the actual speed and / or the target speed is below a certain threshold.

[0014] Furthermore, it is preferable to detect the need for downhill control when the road friction coefficient is below a certain friction coefficient threshold. In particular, the friction coefficient resulting from the combination of road surface and tires is preferably taken into account. Such a friction coefficient can advantageously be detected via slip detection. Such friction coefficient or slip detection can, of course, also be combined with the detection of road gradients and with control / regulation based on actual speed and / or target speed.

[0015] Furthermore, it is advantageous for the wheel-specific braking intervention to include wheel-specific braking torque control, in particular ABS control and / or another function that directly regulates driving stability and / or at least one function that indirectly influences driving stability. Direct control functions are preferred: DSC vehicle controller and / or engine drag torque reduction and / or Adaptive Front Steering and / or rear axle slip angle control and / or integral steering systems. A preferred indirect control is gearshift control. Thus, if the need for downhill control is detected, braking intervention occurs via the ABS control system, enabling wheel-specific braking interventions and slip-dependent braking interventions. This greatly increases the vehicle's stability when driving downhill.

[0016] Furthermore, the preferred approach is simple braking intervention, which involves simultaneous braking intervention on all wheels of the vehicle. This simply distributes the braking force to the front and rear axles via the standard brake cylinder.

[0017] In a further advantageous embodiment, the motor vehicle measures the actual distance to the vehicle ahead using radar, video, ultrasound, and / or laser technology, and thus automatically controls / regulates the target distance. The distance to vehicles ahead can advantageously be detected using a radar in the front of the vehicle. The distance is then normally maintained by simple engine torque control and simple braking interventions. However, if downhill control is necessary, the vehicle is controlled / regulated by individual wheel braking intervention.

[0018] In a further advantageous embodiment, the speed and / or distance are controlled / regulated until the motor vehicle comes to a standstill, and in particular, an automatic restart to the specified target speed and / or the specified target distance is controlled / regulated. Thus, the motor vehicle can automatically navigate through a traffic jam and / or a stop-and-go situation when driving downhill, at least longitudinally dynamically.

[0019] The invention further comprises a motor vehicle with automatic activation of a hill descent control, comprising: - a switching / adjustment device which is designed to set a target speed of the motor vehicle and / or a target distance to a vehicle in front on the driver side, - a detection unit designed to automatically detect the need for downhill control, - a control / regulating device which is designed to control / regulate the motor vehicle to the target speed and / or the target distance merely by adjusting the engine torque and / or a simple braking intervention and / or influencing the transmission and / or influencing the transmission shift when there is no need for downhill control, to control / regulate the motor vehicle to the target speed or a maximum speed and / or the target distance by means of a wheel-individual braking intervention when there is a need for downhill control and to detect the need for downhill control when the predetermined target speed of the motor vehicle is less than a second speed threshold.

[0020] The advantageous embodiments already discussed in the context of the control / regulation method according to the invention naturally apply accordingly to the motor vehicle according to the invention.

[0021] The motor vehicle according to the invention advantageously comprises a steering column stalk and / or buttons on the steering wheel for the driver to set the desired speed and / or desired distance. A separate button for activating a hill descent control is not necessary.

[0022] Preferably, an indicator lamp or display device for the active hill descent control is provided, which shows the driver when the vehicle has automatically switched to hill descent control.

[0023] In an advantageous embodiment, the motor vehicle according to the invention comprises a front-wheel drive, a rear-wheel drive or at least a temporary four-wheel drive.

[0024] The method according to the invention thus combines the functions of cruise control and / or dynamic cruise control and / or adaptive cruise control (with or without stop-and-go function) with a hill descent control function.

Claims

[1] Control / regulation procedures for a motor vehicle include the following steps: - setting by the driver a target speed of the motor vehicle and / or a target distance to a vehicle in front, - automatic detection of a need for downhill control, and - automatic control / regulation of the motor vehicle to the target speed or a maximum speed and / or the target distance by means of a wheel-individual braking intervention when there is a need for downhill control, characterized by - automatic control / regulation of the motor vehicle to the target speed and / or the target distance merely by adjusting the engine torque and / or a simple braking intervention and / or a gearbox control and / or a gearbox control if there is no need for downhill control, - whereby the need for downhill control is detected if the specified target speed of the motor vehicle is less than a second speed threshold. [2] Control / regulation method according to claim 1, characterized by that the need for downhill control is detected when an actual speed of the motor vehicle is less than a first speed threshold, in particular a speed between 7 and 25 km / h. [3] Control / regulation method according to one of the preceding claims, characterized by that the second speed threshold is less than a speed between 7 and 25 km / h. [4] Control / regulation method according to one of the preceding claims, characterized by that the need for downhill control is detected when a road gradient is greater than a certain gradient threshold, in particular greater than 15%. [5] Control / regulation method according to one of the preceding claims, characterized by that the need for downhill control is detected when a road friction coefficient is less than a certain friction threshold. [6] Control / regulation method according to one of the preceding claims, characterized by that the wheel-specific braking intervention includes a wheel-specific braking torque control, in particular an ABS control. [7] Control / regulation method according to one of the preceding claims, characterized by that the simple braking intervention is a common braking intervention on all wheels of the motor vehicle. [8] Control / regulation method according to one of the preceding claims, characterized by that the motor vehicle measures an actual distance to the vehicle in front using radar and / or video and / or ultrasound and / or laser and thus automatically controls / regulates the target distance. [9] Control / regulation method according to one of the preceding claims, characterized bythat the speed and / or the distance are controlled / regulated until the motor vehicle comes to a standstill, and in particular that an automatic restart to the specified target speed and / or the specified target distance is controlled / regulated. [10] Motor vehicle, comprising: - a switching / adjustment device which is designed to set a target speed of the motor vehicle and / or a target distance to a vehicle in front on the driver side, - a detection unit designed to automatically detect the need for downhill control, - a control / regulating device which is designed to control / regulate the motor vehicle to the target speed or a maximum speed and / or the target distance by means of a wheel-individual braking intervention when there is a need for downhill control, characterized by , that - the control / regulating device is designed to control / regulate the motor vehicle to the target speed and / or the target distance merely by adjusting the engine torque and / or a simple braking intervention and / or influencing the transmission and / or influencing the transmission shift when there is no need for downhill control, and to detect the need for downhill control when the predetermined target speed of the motor vehicle is less than a second speed threshold.